To solve this problem, we make use of the formula:
λ = h/mv
where:
λ = wavelength of electron
m = mass of electron = 9.11e-31 kg
v = speed of electron = 1.34×10^5 m/s
h = constant
Hence,
λ = (6.626x10^-34 J-s) / [(9.11e-31 kg)(1.34 x 10^5 m/s)]
λ = 5.43x10^-9 m or 5.43 nm